1. Technical Field
The present invention relates to a liquid ejecting apparatus, such as an ink jet type printer.
2. Related Art
An ink jet type printer which can estimate a residual amount of ink (liquid) in an ink cartridge as an example of a liquid receiving portion has been known as one type of a liquid ejecting apparatus (for example, see JP-A-9-169118).
In the ink jet type printer described above, ink consumption amounts which are obtained based on, for example, amounts of the ink ejected through a liquid ejecting head during a printing operation (a liquid ejection operation) performed on a paper sheet as an example of a printing target are integrated. In a case where an ink receiving amount of the ink cartridge, in a state where the ink cartridge is fully filled with ink, is set to an ink total amount, when an ink residual amount estimation value, which is a difference obtained by subtracting the ink consumption amounts from the ink total amount is calculated, if this ink residual amount estimation value is less than a predetermined ink-empty determination value, it is determined that the ink cartridge is in a so-called ink empty state, that is, a state where a very small amount of ink remains in the ink cartridge.
However, in the ink jet type printer described above, a maintenance process, such as a cleaning operation in which the thickened ink is forcibly discharged, along with, for example, air bubbles, through nozzles formed on the liquid ejecting head, is performed. Even in the maintenance process described above, the ink in the ink cartridge is consumed. Therefore, when the ink residual amount estimation value is smaller than a determination value which is set in accordance with the ink consumption amounts by which the ink can be consumed in the maintenance process, the maintenance process is prevented from being performed because there is a possibility that the ink in the ink cartridge may be exhausted during the maintenance process.
Both an actual amount of the ink ejected through the nozzles of the liquid ejecting head during a printing operation and an actual amount of the ink discharged through the liquid ejecting head during the maintenance process vary in accordance with individual differences caused during manufacturing, by usage environment, or the like. Therefore, the ink consumption amount calculated by internal processing of the ink jet type printer is generally set to a value which is set in the assumption that an individual difference and usage environment are in a condition where the actual ink consumption amount is the maximum.
Accordingly, in some cases, the ink residual amount estimation value which is obtained based on the ink consumption amount calculated by internal processing is smaller than the actual ink residual amount of the ink cartridge. In this case, when the ink residual amount estimation value is less than the determination value described above, it is estimated that the ink residual amount is small, though the amount of the ink remaining in the ink cartridge is actually adequate for performing the maintenance process. As a result, the maintenance process is prevented from being performed.
This problem is not limited to an ink jet type printer but is generally common to a liquid ejecting apparatus capable of ejecting liquid supplied from a liquid receiving portion in which the liquid is received.